The Flashpoint team arguments are a bit lame IMO.....especially considering almost everyone at Star Labs has an appreciation of space/time.
Barry didn't 'change' any timeline. He went back into his own timeline and altered one or two things. That resulted him him being shifted to an entirely different timeline where those same events happened (ie-Cisco's brother dying, Caitlin's powers, etc.)
Furthermore, Barry has openly discussed the 'differences' in these timelines to the folks at Star Labs (and the other teams: Arrow, LOT, Supergirl)....and has told them things that would only make them upset.
He never bothered to tell Cisco his brother was a murderous metahuman on another Earth in league with Zoom.
He could totally confront Diggle and say...."Yeah, I ran back in time and did whatever...."....but try explaining how I changed up your sperm cell so that it resulted in another gender at birth. What happened there? Did Barry run so fast he ended up in Diggle's testicles or something?
The stupidest of all characters has to be this Savitar clown though....
He's UPSET with Barry for screwing with him in the future. But HE is the clown that makes first contact with Barry in the past. Can anyone say PARADOX? Duh Hindu god of speed.
So it's all different timelines Barry is ending up in.....not creating. They all exist simultaneously along the original (and now virtually inaccessible) timeline.